Introduction

Windows 8 comes with multiple input types. Windows 8 devices often have multi-touch screens that enable users to use multiple fingers simultaneously to produce different input interactions such as tapping, dragging, or pinching. The Windows Runtime has a number of different mechanisms for handling touch input, enabling us to create an immersive experience that we can explore with confidence. This Article covers the basics of using touch input (simulating the touch input via VC++ code) in Windows Developer Preview using C++ by Touch Injection API. For other (consumer preview and release preview) you may need to enable UI access permission( check references for this).

Using this article will help all to create application that will help in simulating the Touch inputs like Tap, Drag, Rotate etc. , Consider an application that will convert users mouse event to touch event for those users who does not have Touch screen monitor. Also this will be of great use for Automating any touch based application on windows 8.

Prerequisites

This Article assumes that Reader is updated with these basics requirements

 

Touch Interactions

Touch Interactions are a high-level way of interpreting touch input data into a set of common motions such as tapping, dragging, and pinching. Lets Understand some of the common interactions used in Windows Developer Preview which are as follow:

Interaction	Input Type	Description
Tap	Single Input	One finger touches the screen and lifts up.
Hold	Single Input	One finger touches the screen and stays in place.
Drag	Single Input	One or more fingers touch the screen and move in the same direction.
Pinch/Pan	Multiple Input	Two or more fingers touch the screen and move closer together (Zoom -out) or farther apart (Zoom-in).
Rotate	Multiple Input	Two or more fingers touch the screen and move in a clockwise or counter-clockwise arc.
Cross-slide	Multiple Input	Two finger touches an object and drags it at a right angle to the panning direction.

For windows 8 developer preview this will work as it is but for other windows 8 versions you may need to change UI access permission. Lets see how to simulate these Touch interaction via VC++ code using Touch Injection API.

 

Simulating Tap

By Tap we mean that it has simply touched any portion of screen. In this use case actor takes two action
 

1. Touch down on screen co-ordinate input
2. Lifts Up Touch input

To get above done you need to following 5 steps.

1] Create a Win32 application using visual studio 2011 developer preview. ( with No CLR support and without ATL support)

2] In the WinMain Method Initialize the Touch Injection API refer code below.

POINTER_TOUCH_INFO contact;

InitializeTouchInjection(1, TOUCH_FEEDBACK_DEFAULT); // Here number of contact point is declared as 1.

memset(&contact, 0, sizeof(POINTER_TOUCH_INFO));

 

3] Define the contact Point, this definition contains contact type, contact location ,contact area, pressure and orientation .

 

4] Implementing use case 1 , Injecting Touching down on screen.

 

5] Implementing use case 2 , Injecting Touching Up from screen.

Simulating Hold

 By Hold it mean that Touch is continuously in contact to the screen. In this use case actor takes two action

• Touches the screen
• Keep holding the touch at same  place

  To follow the above scenario repeat all 4 steps mentioned in TAP Simulation and then add the below code as last steps

• Implementing Use case 2 , holding the touch for few second and then lifting the touch up.
  //POINTER_FLAG_UPDATE when use with POINTER_FLAG_INRANGE and POINTER_FLAG_INCONTACT keeps the touch in drag mode with respect to last down Input.

contact.pointerInfo.pointerFlags = POINTER_FLAG_UPDATE | POINTER_FLAG_INRANGE | POINTER_FLAG_INCONTACT;

  for(int i=0;i<100000;i++){        //loops for approx. 1 second causing 1 second HOLD effect

  InjectTouchInput(1, &contact);

  }

  contact.pointerInfo.pointerFlags = POINTER_FLAG_UP;       // Moving the touch Up after Hold Complete

  InjectTouchInput(1, &contact);

   

  Simulating Drag

   By Drag it mean that the user has touched down at any Screen co-ordinate and has moved his finger to another co-ordinate. In this use case the actor has three actions.

  1. Touch down at desired co-ordinate
  2. Dragging from last down co-ordinate to some other.
  3. Lifts Touch Up.

  To follow above scenario repeat all 4 steps of TAP Simulation and then add the below code as last step.

• Implementing use case 2 and 3, wherein we are dragging from one co-ordinate to another and lifting up the touch input. 
  //Setting the Pointer Flag to Drag

  contact.pointerInfo.pointerFlags = POINTER_FLAG_UPDATE | POINTER_FLAG_INRANGE | POINTER_FLAG_INCONTACT;

  for(int i=0;i<100;i++){

  contact.pointerInfo.ptPixelLocation.x--; // updating the X Co-ordinate to x-100 pixels

  InjectTouchInput(1, &contact);

  }

  // Lifts the touch input UP

  contact.pointerInfo.pointerFlags = POINTER_FLAG_UP;

  InjectTouchInput(1, &contact);

   

  Simulating Pinch/Pan

  By Pinch it means that we inject two contact point and drag both towards each other( Zoom-out) or drag both the contact point apart (Zoom-in). In this use case  actor has to following three actions

  1. Injecting two Touch down contact point simultaneously on the screen.
  2. Drag both points inward/outward with respect to each other.
  3. Lifts up both the touch contact point.

  To get the above scenario done follow the following steps.

  1] Initializing the Touch injection API for implementing multiple(in our case two) contact points
  //Taking two contact points and initializing the Touch API accordingly

  POINTER_TOUCH_INFO contact[2];

  InitializeTouchInjection(2, TOUCH_FEEDBACK_DEFAULT);

  memset(&contact[0], 0, sizeof(POINTER_TOUCH_INFO));

  memset(&contact[1], 0, sizeof(POINTER_TOUCH_INFO));

   

  //Check Pointer Id is taken as 0 for contact 0

  contact[0].pointerInfo.pointerType = PT_TOUCH;

  contact[0].pointerInfo.pointerId = 0;          //Id 0 for contact 0

  contact[0].pointerInfo.ptPixelLocation.y = 200;

  contact[0].pointerInfo.ptPixelLocation.x = 300;

  //Defining Touch flag and touchmask for contact 0

  contact[0].touchFlags = TOUCH_FLAG_NONE;

  contact[0].touchMask = TOUCH_MASK_CONTACTAREA | TOUCH_MASK_ORIENTATION | TOUCH_MASK_PRESSURE;

  contact[0].orientation = 90;

  contact[0].pressure = 32000;

  contact[0].rcContact.top = contact[0].pointerInfo.ptPixelLocation.y - 2;

  contact[0].rcContact.bottom = contact[0].pointerInfo.ptPixelLocation.y + 2;

  contact[0].rcContact.left = contact[0].pointerInfo.ptPixelLocation.x  - 2;

  contact[0].rcContact.right = contact[0].pointerInfo.ptPixelLocation.x  + 2;

   

  //Check Pointer Id is taken as 1 for contact 1

  contact[1].pointerInfo.pointerType = PT_TOUCH;

  contact[1].pointerInfo.pointerId = 1;          //Id 0 for contact 1

  contact[1].pointerInfo.ptPixelLocation.y = 200;

  contact[1].pointerInfo.ptPixelLocation.x = 180;

  //Defining Touch flag and touchmask for contact 1

  contact[1].touchFlags = TOUCH_FLAG_NONE;

  contact[1].touchMask = TOUCH_MASK_CONTACTAREA | TOUCH_MASK_ORIENTATION | TOUCH_MASK_PRESSURE;

  contact[1].orientation = 90;

  contact[1].pressure = 32000;

  contact[1].rcContact.top = contact[1].pointerInfo.ptPixelLocation.y - 2;

  contact[1].rcContact.bottom = contact[1].pointerInfo.ptPixelLocation.y + 2;

  contact[1].rcContact.left = contact[1].pointerInfo.ptPixelLocation.x  - 2;

  contact[1].rcContact.right = contact[1].pointerInfo.ptPixelLocation.x  + 2;

   

  2] Injecting both contact point to Down, Implementing use case 1
  //Implementing two touch down for both array of contact point in one go

  contact[0].pointerInfo.pointerFlags = POINTER_FLAG_DOWN | POINTER_FLAG_INRANGE | POINTER_FLAG_INCONTACT;

  contact[1].pointerInfo.pointerFlags = POINTER_FLAG_DOWN | POINTER_FLAG_INRANGE | POINTER_FLAG_INCONTACT;

  InjectTouchInput(2, contact);

   

  3] Dragging both the contact point apart causing he zoom-in , implementing use case 2
  //Setting both the contact point for Drag

  contact[0].pointerInfo.pointerFlags = POINTER_FLAG_UPDATE | POINTER_FLAG_INRANGE | POINTER_FLAG_INCONTACT;

  contact[1].pointerInfo.pointerFlags = POINTER_FLAG_UPDATE | POINTER_FLAG_INRANGE | POINTER_FLAG_INCONTACT;

  for(int i=0; i<100;i++)

  {

  contact[0].pointerInfo.ptPixelLocation.x =300+i;//Zooming in by dragging apart both contact points w.r.t each other

  contact[1].pointerInfo.ptPixelLocation.x =180-i;

  InjectTouchInput(2, contact);

  }

   

  4] Lifts Up both the contact both contact point to Up, Implementing use case 3
  contact[0].pointerInfo.pointerFlags = POINTER_FLAG_UP;

  contact[1].pointerInfo.pointerFlags = POINTER_FLAG_UP;

  InjectTouchInput(2, contact);

   

  Simulating Rotate

  By rotate it mean that two contact points will be dragged in clock wise or anti-clock wise direction with respect to each other. In this use case again actor has three actions.
  
  1. Injecting two Touch down contact point simultaneously on the screen.
  2. Drag both points clock wise/ anti-clock wise with respect to each other.
  3. Lifts up both the touch contact points.

  To implement the above scenario repeat all the steps in shown in Pinch Simulation , but change the step 3 to the code shown below.

• In this step we will rotate the both the touch points to anti-clock wise direction. implementing use case 2
  contact[0].pointerInfo.pointerFlags = POINTER_FLAG_UPDATE | POINTER_FLAG_INRANGE | POINTER_FLAG_INCONTACT;

  contact[1].pointerInfo.pointerFlags = POINTER_FLAG_UPDATE | POINTER_FLAG_INRANGE | POINTER_FLAG_INCONTACT;

  for(int i=0; i<100;i++)

  {

      // implementing the rotation

      if(i%3==0)

      {

      contact[0].pointerInfo.ptPixelLocation.x -= 3;

      contact[1].pointerInfo.ptPixelLocation.x += 3;

       

      contact[0].pointerInfo.ptPixelLocation.y = 200+i;

      contact[1].pointerInfo.ptPixelLocation.y = 200-i;

      }

      InjectTouchInput(2, contact);

  }

   

  Simulating Cross-Slide

  By Cross-Slide we mean two contact points moves in any one direction with respect to screen, simulating a situation where use puts both his figure to touch any picture and drag it to any direction using both of his fingure. In this use case actor has three action.
  
  1. Injecting two Touch down contact point simultaneously on the screen.
  2. Drag both points to any 1 direction.
  3. Lifts up both the touch contact points.

  To implement the above scenario repeat all the steps in shown in Pinch Simulation , but change the step 3 to the code shown below

• Drag Both Touch points to any one direction, implementing use case 2.
  contact[0].pointerInfo.pointerFlags = POINTER_FLAG_UPDATE | POINTER_FLAG_INRANGE | POINTER_FLAG_INCONTACT;

  contact[1].pointerInfo.pointerFlags = POINTER_FLAG_UPDATE | POINTER_FLAG_INRANGE | POINTER_FLAG_INCONTACT;

  for(int i=0; i<100;i++)

  {   

      contact[0].pointerInfo.ptPixelLocation.y = 200+i;

      contact[1].pointerInfo.ptPixelLocation.y = 200+i;

      InjectTouchInput(2, contact);

  }

   

  References

  • Touch Injection sample at http://code.msdn.microsoft.com/windowsdesktop/Touch-Injection-Sample-444d9bf7 (Accessed last on 1/1/2012)
  • Touch input description at http://msdn.microsoft.com/en-us/library/windows/desktop/dd562197%28v=vs.85%29.aspx (Accessed last on 1/1/2012)
  • UI access permission at http://msdn.microsoft.com/en-us/library/ms742884.aspx (Accessed last on 27/09/2012)